fs/ext4/bitmap.c

   1 /*
   2  *  linux/fs/ext4/bitmap.c
   3  *
   4  * Copyright (C) 1992, 1993, 1994, 1995
   5  * Remy Card (card@masi.ibp.fr)
   6  * Laboratoire MASI - Institut Blaise Pascal
   7  * Universite Pierre et Marie Curie (Paris VI)
   8  */
   9
  10 #include <linux/buffer_head.h>
  11 #include <linux/jbd2.h>
  12 #include "ext4.h"
  13
  14 static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0};
  15
  16 unsigned int ext4_count_free(char *bitmap, unsigned int numchars)
  17 {
  18         unsigned int i, sum = 0;
  19
  20         for (i = 0; i < numchars; i++)
  21                 sum += nibblemap[bitmap[i] & 0xf] +
  22                         nibblemap[(bitmap[i] >> 4) & 0xf];
  23         return sum;
  24 }
  25
  26 int ext4_inode_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
  27                                   struct ext4_group_desc *gdp,
  28                                   struct buffer_head *bh, int sz)
  29 {
  30         __u32 hi;
  31         __u32 provided, calculated;
  32         struct ext4_sb_info *sbi = EXT4_SB(sb);
  33
  34         if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
  35                                         EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
  36                 return 1;
  37
  38         provided = le16_to_cpu(gdp->bg_inode_bitmap_csum_lo);
  39         calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  40         if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END) {
  41                 hi = le16_to_cpu(gdp->bg_inode_bitmap_csum_hi);
  42                 provided |= (hi << 16);
  43         } else
  44                 calculated &= 0xFFFF;
  45
  46         return provided == calculated;
  47 }
  48
  49 void ext4_inode_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
  50                                 struct ext4_group_desc *gdp,
  51                                 struct buffer_head *bh, int sz)
  52 {
  53         __u32 csum;
  54         struct ext4_sb_info *sbi = EXT4_SB(sb);
  55
  56         if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
  57                                         EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
  58                 return;
  59
  60         csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  61         gdp->bg_inode_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
  62         if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
  63                 gdp->bg_inode_bitmap_csum_hi = cpu_to_le16(csum >> 16);
  64 }
  65
  66 int ext4_block_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
  67                                   struct ext4_group_desc *gdp,
  68                                   struct buffer_head *bh, int sz)
  69 {
  70         __u32 hi;
  71         __u32 provided, calculated;
  72         struct ext4_sb_info *sbi = EXT4_SB(sb);
  73
  74         if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
  75                                         EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
  76                 return 1;
  77
  78         provided = le16_to_cpu(gdp->bg_block_bitmap_csum_lo);
  79         calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  80         if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END) {
  81                 hi = le16_to_cpu(gdp->bg_block_bitmap_csum_hi);
  82                 provided |= (hi << 16);
  83         } else
  84                 calculated &= 0xFFFF;
  85
  86         if (provided == calculated)
  87                 return 1;
  88
  89         ext4_error(sb, "Bad block bitmap checksum: block_group = %u", group);
  90         return 0;
  91 }
  92
  93 void ext4_block_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
  94                                 struct ext4_group_desc *gdp,
  95                                 struct buffer_head *bh, int sz)
  96 {
  97         __u32 csum;
  98         struct ext4_sb_info *sbi = EXT4_SB(sb);
  99
 100         if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
 101                         EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
 102                 return;
 103
 104         csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
 105         gdp->bg_block_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
 106         if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END)
 107                 gdp->bg_block_bitmap_csum_hi = cpu_to_le16(csum >> 16);
 108 }